The effect of region of interest strategies on apparent diffusion coefficient assessment in patients treated with palliative radiation therapy to brain metastases

Faisal Mahmood, Helle Hjorth Johannesen, Poul Geertsen, Giske F. Opheim, Rasmus H. Hansen

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

Abstrakt

Background. Although diffusion-weighted magnetic resonance imaging (DW-MRI) is widely used in radiation therapy (RT) response studies, no standard of delineating the region of interest (ROI) exists. In this retrospective study, we evaluate the effect of four ROI strategies on the apparent diffusion coefficients (ADC) in patients receiving palliative RT to brain metastases.
Material and methods. Twenty-two metastases from nine patients, treated with whole-brain irradiation (30 Gy in 10 fractions) were analyzed. Patients were scanned with a 1T MR system to acquire DW- (eight b-values), T2 * W-, T2Wand T1W scans, before start of RT (pre-RT) and at the 9th/10th fraction (end-RT). The following ROI strategies were applied. ROI b800 and ROI b0 : Entire tumor volume visible on DW(b 800 s/mm 2 ) and DW(b 0 s/mm 2 ) images, respectively. ROI b800vi : Viable tumor volume based on DW(b 800 s/mm 2 ). ROI b800rep : ROI b800 from pre-RT scan replicated to end-RT scan. Delineations were aided by co-registered T1W, T2W and T2 * W images. ADC was estimated with two mono-exponential fits and one bi-exponential fit.
Results. Differences in absolute ADC values were non-signifi cant across ROI strategy independent of fi tting method, while signifi cantly different between fi tting methods. Evaluation of individual metastases showed that ROI strategies
disagreed on the relative ADC change (from pre-RT to end-RT) in 13 of the 22 metastases when all fi tting methods were added up.
Conclusion. The ROI strategies have an effect on the relative ADC change, which may be important for the assessment of individual patient’s response to RT and the interpretation of the current literature.
OriginalsprogEngelsk
TidsskriftActa Oncologica
Vol/bind54
Udgave nummer9
Sider (fra-til)1529-1534
ISSN0001-6381
DOI
StatusUdgivet - 2015
Udgivet eksterntJa

Fingeraftryk Dyk ned i forskningsemnerne om 'The effect of region of interest strategies on apparent diffusion coefficient assessment in patients treated with palliative radiation therapy to brain metastases'. Sammen danner de et unikt fingeraftryk.

Citationsformater